{-# options_haddock prune #-}

-- |Description: Process Interpreters, Internal
module Polysemy.Process.Interpreter.Process where

import Control.Concurrent.STM.TBMQueue (TBMQueue)
import Polysemy.Conc.Async (withAsync_)
import qualified Polysemy.Conc.Data.QueueResult as QueueResult
import qualified Polysemy.Conc.Effect.Queue as Queue
import Polysemy.Conc.Effect.Queue (Queue)
import Polysemy.Conc.Effect.Race (Race)
import Polysemy.Conc.Effect.Scoped (Scoped)
import Polysemy.Conc.Interpreter.Queue.TBM (interpretQueueTBMWith, withTBMQueue)
import Polysemy.Conc.Interpreter.Scoped (interpretScopedResumableWith_)
import Polysemy.Resume (Stop, resumeOr, stop, type (!!))
import Prelude hiding (fromException)

import Polysemy.Process.Data.ProcessError (ProcessError (Terminated))
import qualified Polysemy.Process.Effect.Process as Process
import Polysemy.Process.Effect.Process (Process)
import qualified Polysemy.Process.Effect.ProcessOutput as ProcessOutput
import Polysemy.Process.Effect.ProcessOutput (ProcessOutput)
import qualified Polysemy.Process.Effect.SystemProcess as SystemProcess
import Polysemy.Process.Effect.SystemProcess (SystemProcess, withSystemProcess)
import Polysemy.Process.Interpreter.ProcessOutput (
  interpretProcessOutputId,
  interpretProcessOutputLines,
  interpretProcessOutputText,
  interpretProcessOutputTextLines,
  )

newtype In a =
  In { unIn :: a }
  deriving stock (Eq, Show)

newtype Out a =
  Out { unOut :: a }
  deriving stock (Eq, Show)

newtype Err a =
  Err { unErr :: a }
  deriving stock (Eq, Show)

data ProcessQueues o e =
  ProcessQueues {
    pqIn :: TBMQueue (In ByteString),
    pqOut :: TBMQueue (Out o),
    pqErr :: TBMQueue (Err e)
  }

interpretQueues ::
  Members [Resource, Race, Embed IO] r =>
  ProcessQueues o e ->
  InterpretersFor [Queue (In ByteString), Queue (Out o), Queue (Err e)] r
interpretQueues (ProcessQueues inQ outQ errQ) =
  interpretQueueTBMWith errQ .
  interpretQueueTBMWith outQ .
  interpretQueueTBMWith inQ

handleProcessWithQueues ::
  ∀ o e m r a .
  Members [Queue (In ByteString), Queue (Out o), Queue (Err e), Stop ProcessError] r =>
  Process ByteString o e m a ->
  Sem r a
handleProcessWithQueues = \case
  Process.Recv ->
    Queue.read >>= \case
      QueueResult.Closed ->
        stop (Terminated "closed")
      QueueResult.NotAvailable ->
        stop (Terminated "impossible: empty")
      QueueResult.Success (Out msg) ->
        pure msg
  Process.RecvError ->
    Queue.read >>= \case
      QueueResult.Closed ->
        stop (Terminated "closed")
      QueueResult.NotAvailable ->
        stop (Terminated "impossible: empty")
      QueueResult.Success (Err msg) ->
        pure msg
  Process.Send msg -> do
    whenM (Queue.closed @(In ByteString)) (stop (Terminated "closed"))
    Queue.write (In msg)

withSTMResources ::
  ∀ o e r a .
  Members [Resource, Embed IO] r =>
  Int ->
  (ProcessQueues o e -> Sem r a) ->
  Sem r a
withSTMResources qSize action = do
  withTBMQueue qSize \ inQ ->
    withTBMQueue qSize \ outQ ->
      withTBMQueue qSize \ errQ ->
        action (ProcessQueues inQ outQ errQ)

withQueues ::
  Members [Race, Resource, Embed IO] r =>
  Int ->
  InterpretersFor [Queue (In ByteString), Queue (Out o), Queue (Err e)] r
withQueues qSize action =
  withSTMResources qSize \ qs -> interpretQueues qs action

outputQueue ::
  ∀ pipe chunk err r .
  Coercible (pipe chunk) chunk =>
  Members [SystemProcess !! err, ProcessOutput chunk, Queue (pipe chunk), Embed IO] r =>
  Bool ->
  Sem (SystemProcess : r) ByteString ->
  Sem r ()
outputQueue discardWhenFull readChunk = do
  spin ""
  where
    spin buffer =
      resumeOr @err readChunk (write buffer) (const (Queue.close @(pipe chunk)))
    write buffer msg = do
      (chunks, newBuffer) <- ProcessOutput.chunk buffer msg
      for_ chunks \ (coerce @chunk @(pipe chunk) -> c) ->
        if discardWhenFull then void (Queue.tryWrite c) else Queue.write c
      spin newBuffer

inputQueue ::
  ∀ err r .
  Members [SystemProcess !! err, Queue (In ByteString), Embed IO] r =>
  (ByteString -> Sem (SystemProcess : r) ()) ->
  Sem r ()
inputQueue writeChunk =
  spin
  where
    spin =
      Queue.read >>= \case
        QueueResult.Success (In msg) ->
          resumeOr @err (writeChunk msg) (const spin) (const (Queue.close @(In ByteString)))
        _ ->
          unit

type ScopeEffects o e err =
  [Queue (In ByteString), Queue (Out o), Queue (Err e), SystemProcess !! err]

scope ::
  ∀ o e resource err r .
  Member (Scoped resource (SystemProcess !! err)) r =>
  Members [ProcessOutput e, ProcessOutput o, Resource, Race, Async, Embed IO] r =>
  Bool ->
  Int ->
  InterpretersFor (ScopeEffects o e err) r
scope discard qSize =
  withSystemProcess @resource .
  withQueues qSize .
  withAsync_ (outputQueue @Err @e @err discard SystemProcess.readStderr) .
  withAsync_ (outputQueue @Out @o @err discard SystemProcess.readStdout) .
  withAsync_ (inputQueue @err SystemProcess.writeStdin)

-- |Interpret 'Process' with a system process resource whose file descriptors are connected to three 'TBMQueue's,
-- deferring decoding of stdout and stderr to the interpreters of two 'ProcessOutput' effects.
interpretProcess ::
  ∀ resource err o e r .
  Member (Scoped resource (SystemProcess !! err)) r =>
  Members [ProcessOutput o, ProcessOutput e, Resource, Race, Async, Embed IO] r =>
  -- |Whether to discard output chunks if the queue is full or block.
  Bool ->
  -- |Maximum number of chunks allowed to be queued for each of the three standard pipes.
  Int ->
  InterpreterFor (Scoped () (Process ByteString o e) !! ProcessError) r
interpretProcess discard qSize =
  interpretScopedResumableWith_ @(ScopeEffects o e err) (scope @o @e @resource discard qSize) handleProcessWithQueues

-- |Interpret 'Process' with a system process resource whose file descriptors are connected to three 'TBMQueue's,
-- producing 'ByteString's.
interpretProcessByteString ::
  ∀ resource err r .
  Members [Scoped resource (SystemProcess !! err), Resource, Race, Async, Embed IO] r =>
  -- |Whether to discard output chunks if the queue is full.
  Bool ->
  -- |Maximum number of chunks allowed to be queued for each of the three standard pipes.
  Int ->
  InterpreterFor (Scoped () (Process ByteString ByteString ByteString) !! ProcessError) r
interpretProcessByteString discard qSize =
  interpretProcessOutputId .
  interpretProcess @resource @err discard qSize .
  raiseUnder

-- |Interpret 'Process' with a system process resource whose file descriptors are connected to three 'TBMQueue's,
-- producing chunks of lines of 'ByteString's.
interpretProcessByteStringLines ::
  ∀ resource err r .
  Members [Scoped resource (SystemProcess !! err), Resource, Race, Async, Embed IO] r =>
  -- |Whether to discard output chunks if the queue is full.
  Bool ->
  -- |Maximum number of chunks allowed to be queued for each of the three standard pipes.
  Int ->
  InterpreterFor (Scoped () (Process ByteString ByteString ByteString) !! ProcessError) r
interpretProcessByteStringLines discard qSize =
  interpretProcessOutputLines .
  interpretProcess @resource @err discard qSize .
  raiseUnder

-- |Interpret 'Process' with a system process resource whose file descriptors are connected to three 'TBMQueue's,
-- producing 'Text's.
interpretProcessText ::
  ∀ resource err r .
  Members [Scoped resource (SystemProcess !! err), Resource, Race, Async, Embed IO] r =>
  -- |Whether to discard output chunks if the queue is full.
  Bool ->
  -- |Maximum number of chunks allowed to be queued for each of the three standard pipes.
  Int ->
  InterpreterFor (Scoped () (Process ByteString Text Text) !! ProcessError) r
interpretProcessText discard qSize =
  interpretProcessOutputText .
  interpretProcess @resource @err discard qSize .
  raiseUnder

-- |Interpret 'Process' with a system process resource whose file descriptors are connected to three 'TBMQueue's,
-- producing chunks of lines of 'Text's.
interpretProcessTextLines ::
  ∀ resource err r .
  Members [Scoped resource (SystemProcess !! err), Resource, Race, Async, Embed IO] r =>
  -- |Whether to discard output chunks if the queue is full.
  Bool ->
  -- |Maximum number of chunks allowed to be queued for each of the three standard pipes.
  Int ->
  InterpreterFor (Scoped () (Process ByteString Text Text) !! ProcessError) r
interpretProcessTextLines discard qSize =
  interpretProcessOutputTextLines .
  interpretProcess @resource @err discard qSize .
  raiseUnder